Design Optimisation of the Graz Cycle Prototype Plant

Content Provider	Semantic Scholar
Author	Jericha, H. Göttlich, Emil Sanz, Wolfgang Heitmeir, Franz
Copyright Year	2003
Abstract	Introduction of closed cycle gas turbines with their capability of retaining combustion generated CO2 can offer a valuable contribution to the Kyoto goal and to future power generation. The use of well established gas turbine technology enhanced by recent research results enables designers even today to present proposals for prototype plants. Research and development work of TTM Institute of Graz University of Technology since the 90's has lead to the Graz Cycle, a zero emission power cycle of highest efficiency and with most positive features. In this work the design for a prototype plant based on current technology as well as cutting-edge turbomachinery is presented. The object of such a plant shall be the demonstration of operational capabilities and shall lead to the planning and design of much larger units of highest reliability and thermal efficiency. INTRODUCTION Optimisation of a thermal power plant starts with the optimisation of the cycle scheme i.e. the thermodynamic relations of cycle media in the process of power production. Like in any heat engine it involves according to Carnot ́s rule introduction of fuel heat input at maximum possible temperature, compression and expansion at maximum compressor and turbine efficiency and release of non-convertible heat to ambient at minimum loss. The relations of media within the cycle have to be optimised regarding heat transfer, pressure loss, material cooling, in the many connections that have been invented and are in use today. Turbomachinery design has to be optimised first of all in terms of flow efficiency, high temperature blade cooling methods, rotor speed and turbine-compressor driving connections in any case on the basis of sound rotor dynamics. Surface heat exchangers such as steam generators, feed water heaters and condensers have to be carefully studied to minimize costs in general and to minimize requirements of high temperature metal for heat transfer surfaces and associated pressure losses. Closed cycle gas turbines of zero emission with the capability of capturing or retaining combustion generated CO2 require novel cycle solutions. A general comparison between different solutions of CO2 retaining plants is given very detailed in [16]. Among them was the so-called Graz Cycle system, which has been presented by the authors in several papers at previous conferences (CIMAC, ASME, VDI, [1 9]). Any fossil fuel gas (preferable with low nitrogen content) is proposed to be combusted with oxygen so that mainly only the two combustion products CO2 and H2O are generated. Oxygen can be generated from air by air separation plants which are in use worldwide with great outputs in steel making industry and even in enhanced oil recovery. Although the Graz Cycle is suited for all kinds of fossil fuels, for natural gas fuel it seems reasonable to reform CH4 to CO + H2. Hydrogen can be separated and burned in an air breathing gas turbine, a solution which reduces the oxygen requirements considerably [10]. But in using oxygen blown coal gas as a fuel a Graz Cycle plant is most effective in retaining CO2 and in use of oxygen. The thermodynamic details of a prototype Graz Cycle plant of 92 MW power fired with oxygen blown coal fuel gas were presented to VDI in 2000 [9]. This cycle scheme shall be used here as the basis of turbomachinery optimisation discussion. A general layout of all components, especially turbomachines, combustion chamber and burners, and general arrangement with gears and electric generators was presented at ASME IGTI conference 2002 [11]. The object of this paper is to present this kind of zero emission cycle optimised for highest thermal cycle efficiency. The deliberations which have led to the cycle scheme as well as to the special design of blading and rotors are shown. This work specially concentrates on the high temperature turbine and its first transonic stage with the associated innovative steam cooling system.
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Language	English
Access Restriction	Open
Subject Keyword	Arabic numeral 0 Burn injury CNS disorder Carbon Dioxide Closed system Coal Compression Computer cooling Cool - action Desktop virtualization Fever Fossil Fuels Gear Device Component Heater, device Hydrogen Large Mathematical optimization Microwave Natural Gas Oxygen Paper Power Plants Prototype R.O.T.O.R. Requirement Solutions Steam Steel The Third Manifesto Thermodynamics Trichotillomania Water
Content Type	Text
Resource Type	Article